The session result doesn't give much information - just number of players and max players and session name. Is there any way to tell how many of the players are spectators? Any way to pass other user information through from the server to clients finding matches?
It might require you to modify the Oculus plugin; in OVR_Requests_Room.h it says there are two public fields Description and Data Store (which is a key/value map for moderated, private, and matchmaking rooms). You may be able to use those. I have not yet seen anything similar that is built into Unreal's base session interface.